pkgs/nixfiles: Ask before doing a system upgrade from Hydra

pkgs/nixfiles/nixfiles-system-upgrade.sh

@@ -3,17 +3,22 @@
 set -euo pipefail
 
 ALLOW_REBOOT=
+NO_CONFIRM=
 
 while [[ $# -gt 0 ]]; do
 	case $1 in
 		--allow-reboot)
 			ALLOW_REBOOT=1
 			shift
-			;;
+		;;
+		--no-confirm)
+			NO_CONFIRM=1
+			shift
+		;;
 		*)
 			echo "Unknown option $1"
 			exit 1
-			;;
+		;;
 	esac
 done
 
@@ -22,6 +27,17 @@ HYDRA_JOB_URL="https://hydra.clerie.de/job/nixfiles/nixfiles/nixosConfigurations
 echo "Fetching job output from ${HYDRA_JOB_URL}"
 STORE_PATH="$(curl --fail -s -L -H "Accept: application/json" "${HYDRA_JOB_URL}" | jq -r ".buildoutputs.out.path")"
 
+if [[ -z $NO_CONFIRM ]]; then
+	echo ""
+	echo "  ! WARNING !"
+	echo ""
+	echo "  You are about to upgrade ${HOSTNAME} to ${STORE_PATH}."
+	echo "  This can be an older version than currently running on this system."
+	echo ""
+	read -e -r -p "Continue?" confirm
+	echo "$confirm" > /dev/null
+fi
+
 echo "Download ${STORE_PATH}"
 nix copy --from "https://nix-cache.clerie.de" "${STORE_PATH}"